Bidirectional optical transceiver

ABSTRACT

An apparatus, system and method for facilitating higher bandwidth communication in a data center using existing multi-mode fibers. A first transceiver within a first device transmits Ethernet traffic to a second device over first and second optical fibers and receives return optical signals over the same first and second optical devices. By varying the wavelengths between the transmitted and received optical signals, the same optical fibers can be used to both transmit and receive optical signals. A second transceiver within the same housing as the first transceiver performs the same function. In this fashion, one device can be coupled to four bidirectional optical fibers, each transmitting and receiving optical signals at 20 Gbps.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.14/557,326, filed Dec. 1, 2014, entitled “2×40 GBPS BIDI OPTICALTRANSCEIVER,” which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to optical communications for improvingbandwidth in fiber optic networks using existing multi-mode opticalfibers.

BACKGROUND

Currently, legacy data centers are built to accommodate a link speed of10 Gigabytes per second (Gbps) for transmission of Ethernet data overoptical fibers. However, each fiber is actually capable of handling 20Gbps. There is currently a market transition to change the link speedfrom 10 Gbps Ethernet to 40 Gbps Ethernet in the data center.

BRIEF DESCRIPTION OF THE DRAWINGS

There are shown in the drawings embodiments that are presently preferredit being understood that the disclosure is not limited to thearrangements and instrumentalities shown, wherein:

FIG. 1 illustrates a full-duplex communication of Ethernet traffic overfour multi-mode optical fibers between first and second devicesincorporating the principles of the present disclosure;

FIG. 2 is a block diagram of a QSFP module used in connection with thepresent disclosure;

FIG. 3 illustrates a perspective view of the QSFP module housing;

FIG. 4 illustrates a perspective view of the QSFP module housing coupledto four optical fibers; and

FIG. 5 illustrates a flowchart depicting steps taken by an example ofthe present disclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The detailed description set forth below is intended as a description ofvarious configurations of the subject technology and is not intended torepresent the only configurations in which the subject technology can bepracticed. The appended drawings are incorporated herein and constitutea part of the detailed description. The detailed description includesspecific details for the purpose of providing a more thoroughunderstanding of the subject technology. However, it will be clear andapparent that the subject technology is not limited to the specificdetails set forth herein and may be practiced without these details. Insome instances, structures and components are shown in block diagramform in order to avoid obscuring the concepts of the subject technology.

Overview

In one aspect of the present disclosure, an apparatus is provided, wherethe apparatus includes an electrical interface for receiving apredetermined bandwidth of Ethernet traffic, an optical interface forreceiving a plurality of optical fibers, a modem configured to allocatethe received predetermined bandwidth of Ethernet traffic into first andsecond optical portions, a first optical transceiver configured totransmit, via the optical interface, the first optical portion ofEthernet traffic over a first optical fiber at a first wavelength andover a second optical fiber at a second wavelength, and a second opticaltransceiver configured to transmit, via the optical interface, thesecond optical portion of the Ethernet traffic over a third opticalfiber at a third wavelength and over a fourth optical fiber at a fourthwavelength.

In another aspect, a system is provided, the system including a firstdevice, a second device, and a plurality of optical fibers coupledbetween the first device and the second device. The first deviceincludes a modem configured to allocate a predetermined bandwidth ofEthernet traffic into first and second optical portions, a first opticaltransceiver configured to transmit the first optical portion of thepredetermined bandwidth of Ethernet traffic over a first optical fiberof the plurality of optical fibers at a first wavelength and over asecond optical fiber of the plurality of optical fibers at a secondwavelength, and a second optical transceiver configured to transmit thesecond optical portion of the predetermined bandwidth of Ethernettraffic over a third optical fiber of the plurality of optical fibers ata third wavelength and over a fourth optical fiber of the plurality ofoptical fibers at a fourth wavelength.

In yet another aspect of the present disclosure, a method is providedwhere the method includes, transmitting, from a first device to a seconddevice, a first portion of a predetermined bandwidth of Ethernet trafficover a first optical fiber at a first wavelength and over a secondoptical fiber at a second wavelength, receiving, by the first devicefrom the second device, a first return optical signal over the firstoptical fiber at a wavelength different from the first wavelength and asecond return optical signal over the second optical fiber at awavelength that is different from the second wavelength, transmitting,from the first device to the second device, a second portion of thepredetermined bandwidth of Ethernet traffic over a third optical fiberat a third wavelength and over a fourth optical fiber at a fourthwavelength, and receiving, by the first device from the second device, athird return optical signal over the third optical fiber at a wavelengththat is different from the third wavelength and a fourth return opticalsignal over the fourth optical fiber at a wavelength that is differentfrom the fourth wavelength.

DETAILED DESCRIPTION

In order to accommodate the previously mentioned market transition tochange the link speed from 10 Gbps Ethernet in the data center, theexisting fiber would need to be replaced. Changing the fibers is acostly process for data centers, particularly large data centers wherelabor costs and material costs would make the transition an exorbitantand perhaps cost-prohibitive undertaking. The present disclosuredescribes an apparatus and method for improved bandwidth capabilities ina data center using existing fiber optic fibers. FIG. 1 illustrates ahigh-level diagram of an optical communication system in a data center10. In the optical communication system, network traffic, for example,Ethernet traffic, is communicated between a first device 20 and a seconddevice 30, denoted in FIG. 1 as Device A and Device B, respectively. Aplurality of optical fibers are coupled to each of device 20 and device30 in order to carry optical signals between the two devices.

According to the example shown in FIG. 1, each of four multi-modefibers, 40, 42, 44, and 46 carries a portion of a predeterminedbandwidth of Ethernet traffic in the form of optical signals betweendevice 20 and device 30. In one example, optical fibers 40 and 42 carrya first portion of the predetermined bandwidth of Ethernet traffic fromdevice 20 to device 30 and optical fibers 44 and 46 carry a secondportion of the predetermined bandwidth of Ethernet traffic from device20 to device 30. In one example, optical fiber 40 carries a firstoptical signal 48 at a first wavelength λ1 from device 20 to device 30.Optical fiber 42 carries a second optical signal 52 at a secondwavelength λ2 from device 20 to device 30. Optical fiber 44 carries athird optical signal 56 at a third wavelength λ3 from device 20 todevice 30. Optical fiber 46 carries a fourth optical signal 60 at afourth wavelength λ4 from device 20 to device 30.

Optical fibers 40, 42, 44, and 46 can be full-duplex fibers, capable oftransmitting and receiving optical signals in the same fiber. This isaccomplished due to the differences in wavelengths between thetransmitted optical signals. For example, optical fiber 40 can carry afirst return optical signal 50 from device 30 to device 20 having afifth wavelength λ5 that is different from the first wavelength λ1, thusallowing both first optical signal 48 and first return optical signal 50to be carried by the same fiber, i.e., optical fiber 40.

Similarly, optical fiber 42 can carry a second return optical signal 54from device 30 to device 20 having a sixth wavelength λ6 that isdifferent from the second wavelength λ2, thus allowing both the secondoptical signal 52 and the second return optical signal 54 to be carriedby the same fiber, i.e., optical fiber 42. Optical fiber 44 can carry athird return optical signal 58 from device 30 to device 20 having aseventh wavelength λ7 that is different from wavelength λ3, thusallowing both the third optical signal 56 and the third return opticalsignal 58 to be carried by the same fiber, i.e., fiber 44. Finally,optical fiber 46 can carry a fourth return optical signal 62 from device30 to device 20 having an eighth wavelength λ8 that is different fromthe fourth wavelength λ4, thus allowing both the fourth optical signal60 and the fourth return optical signal 62 to be carried on the samefiber, i.e., fiber 46.

FIG. 2 illustrates an example of the present disclosure where device 20is a Quad Small Form-factor Pluggable (QSFP) module 80. QSFP module 80can house transceiver 1 66 and transceiver 2 68. Transceiver 1 66 andtransceiver 2 68 each include the necessary components, includingmodems, to convert the incoming electrical signals of the Ethernettraffic to optical signals for transmission over optical fibers 40, 42,44, and 46 and to convert incoming optical signals from an optical fiberback into electronic signals, as is known in the art. QSFP 80 alsoincludes an electrical interface 74 that receives electrical signals andan optical interface 78 that receives a plurality of optical fibers.Note that the use of QSFP module 80 to house the electrical componentsof device 20 is merely exemplary and other modules or housings may beused. Ethernet traffic in the form of electrical signals is received byQSFP module 80 at electrical interface 74 and these signals convertedinto optical signals and transmitted along full-duplex optical cables40, 42, 44, and 46 in the manner described above.

Using the techniques illustrated in FIG. 1, QSFP 80 receives apredetermined bandwidth of Ethernet traffic in the form of electricalsignals that is to be sent to second device 30. In one example, apredetermined bandwidth of Ethernet traffic is 80 Gbps and the firstportion of predetermined bandwidth of Ethernet traffic allocated totransceiver 1 66 is 40 Gbps and the second portion of Ethernet trafficallocated to transceiver 2 68 is 40 Gbps. In this example, electricalsignals are received at electrical interface 74 of QSFP module 80 alonglinks 70 and 71 at 20 Gb per link. Transceiver 1 66 converts theseelectrical signals, which form the first portion of the predeterminedbandwidth of Ethernet traffic, to optical signals which are transmittedat optical interface 78 over optical links 40 and 42 to device 30 at 20Gb per link. Similarly, electrical signals are received at electricalinterface 74 of QSFP module 80 along links 72 and 73 at 20 Gb per link.Transceiver 2 68 converts these electrical signals, which form thesecond portion of the predetermined bandwidth of Ethernet traffic, tooptical signals which are transmitted at optical interface 78 overoptical links 44 and 46 to device 30 at 20 Gb per link.

Incoming optical signals from device 30 over links 40 and 42 areconverted back to electrical signals by transceiver 1 66 and, in oneexample, transmitted to other devices along links 75 and 77 viaelectrical interface 74 at 20 Gb per link. Similarly, incoming opticalsignals over links 44 and 46 are converted back to electrical signals bytransceiver 2 68 and, in one example, transmitted to other devices alonglinks 79 and 81 via electrical interface 74 at 20 Gb per link.

FIGS. 3 and 4 illustrate QSFP module 80 which, as described in greaterdetail above, includes modem 64 and transceivers 66 and 68 such thatsignals received by QSFP module 80 at its electrical interface 74 areconverted to optical signals in the manner described above andtransmitted to another device, i.e., device 30. As shown in FIG. 3,optical interface 78 of device 20 includes four ports, each portconfigured to receive an optical fiber. Advantageously, a single QSFPmodule 80 is used to house transceivers 66 and 68, and which via itsoptical interface 78, is able to couple to four optical fibers in orderto transmit and receive optical signals. In certain embodiments QSFPmodule 80 can include an optical interface 78 that can receive more orless than four optical cables. The dimensions of QSFP module 80 can bemodified accordingly in order to house the electrical componentsincluding modem 64, transceiver A 66 and transceiver B 68 and itsoptical interface 78 configured to receive two pairs of optical fibers,i.e., a first pair of optical fibers (optical fibers 40 and 42) and asecond pair of optical fibers (optical fibers 44 and 46) as shown inFIG. 4. QSFP module 80 can also include one or more heat sinks to safelyaccount for heat dissipation due to the modified size of QSFP 80.

FIG. 5 is a flowchart showing the interaction between first device 20and second device 30 utilizing the principles of the present disclosure.At step 80, first device 20 transmits to a second device 30, a firstportion of a predetermined bandwidth of Ethernet traffic, the firstportion including signal 48 transmitted over a first optical fiber 40 ata first wavelength λ1 and signal 52 transmitted over a second opticalfiber 42 at a second wavelength λ2. At step 82, first device 20 receivesfrom second device 30, a first return optical signal 50 over the firstoptical fiber 40 at a wavelength λ5 different from the first wavelengthλ1 and a second return optical signal 54 over the second optical fiber42 at a wavelength λ6 that is different from the second wavelength λ2.

Continuing to refer to FIG. 5, at step 84, first device 20 transmits tosecond device 30, a second portion of the predetermined bandwidth ofEthernet traffic, the second portion including signal 56 transmittedover a third optical fiber 44 at a third wavelength λ3 and includingsignal 60 transmitted over a fourth optical fiber at a fourth wavelengthλ4. At step 86, first device 20 receives from second device 30, a thirdreturn optical signal 58 over the third optical fiber 44 at a wavelengthλ7 that is different from the third wavelength λ3 and a fourth returnoptical signal 62 over the fourth optical fiber 46 at a wavelength λ8that is different from the fourth wavelength λ4.

The present disclosure provides techniques for facilitating higherbandwidth in a data center using multi-mode fibers and full-duplexoptical communications. Specifically, the present disclosure describesmethods for compressing two bidirectional transceivers within a singlemodule, i.e., a QSFP module. Combining transceivers in this fashionimproves integration of the electronic components therein and reducesthe overall data center/enterprise network switch footprint.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.”

A phrase such as an “aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations. Aphrase such as an aspect may refer to one or more aspects and viceversa. A phrase such as a “configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A phrase such as a configuration mayrefer to one or more configurations and vice versa.

The word “exemplary” is used herein to mean “serving as an example orillustration.” Any aspect or design described herein as “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects or designs.

The specification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense. It will, however, beevident that various modifications and changes may be made thereuntowithout departing from the broader spirit and scope of various aspectsof the disclosure as set forth in the claims.

What is claimed is:
 1. An apparatus comprising: an electrical interfacefor receiving a predetermined bandwidth of Ethernet traffic; a QuadSmall Form-Factor Pluggable (QSFP) optical interface configured toprovide a bidirectional data interface over a plurality of opticalfibers; a modem configured to allocate the predetermined bandwidth ofEthernet traffic into a first portion and a second portion; and a firstoptical transceiver configured to transmit, via the QSFP opticalinterface, the first portion of Ethernet traffic over a first opticalfiber at a first wavelength and over a second optical fiber at a secondwavelength; wherein the first optical fiber is configured tobidirectionally carry two wavelengths of light, the second optical fiberis configured to bidirectionally carry two wavelengths of lightdifferent than the first optical fiber.
 2. The apparatus of claim 1,further comprising: a second optical transceiver configured to transmit,via the QSFP optical interface, the second portion of the Ethernettraffic over a third optical fiber at a third wavelength and over afourth optical fiber at a fourth wavelength.
 3. The apparatus of claim1, wherein the first optical transceiver is further configured to:receive a first return optical signal over the first optical fiber at awavelength different from the first wavelength; and receive a secondreturn optical signal over the second optical fiber at a wavelength thatis different from the second wavelength, and wherein the second opticaltransceiver is further configured to receive a third return opticalsignal over the third optical fiber at a wavelength that is differentfrom the third wavelength and receive a fourth return optical signalover the fourth optical fiber at a wavelength that is different from thefourth wavelength.
 4. The apparatus of claim 1, wherein thepredetermined bandwidth of Ethernet traffic is 80 Gbps.
 5. The apparatusof claim 1, wherein the first portion and the second portion of thepredetermined bandwidth of Ethernet traffic are each 40 Gbps.
 6. Theapparatus of claim 1, wherein the electrical interface receives thepredetermined bandwidth of Ethernet traffic over two links, each linkconfigured for carrying a signal at 20 Gbps.
 7. A system comprising: afirst device; a second device; and a plurality of optical fibers coupledbetween the first device and the second device; the first devicecomprising: a modem configured to allocate a predetermined bandwidth ofEthernet traffic into first and second portions; and a first opticaltransceiver configured to transmit the first portion of thepredetermined bandwidth of Ethernet traffic over a first optical fiberof the plurality of optical fibers at a first wavelength and over asecond optical fiber of the plurality of optical fibers at a secondwavelength; wherein the first optical fiber is configured tobidirectionally carry two wavelengths of light, the second optical fiberis configured to bidirectionally carry two wavelengths of lightdifferent than the first optical fiber.
 8. The system of claim 7,further comprising: a second optical transceiver configured to transmitthe second portion of the predetermined bandwidth of Ethernet trafficover a third optical fiber of the plurality of optical fibers at a thirdwavelength and over a fourth optical fiber of the plurality of opticalfibers at a fourth wavelength.
 9. The system of claim 8, wherein thefirst optical transceiver is further configured to receive a firstreturn optical signal over the first optical fiber at a wavelengthdifferent from the first wavelength, and receive a second return opticalsignal over the second optical fiber at a wavelength that is differentfrom the second wavelength, and wherein the second optical transceiveris further configured to receive a third return optical signal over thethird optical fiber at a wavelength that is different from the thirdwavelength and receive a fourth return optical signal over the fourthoptical fiber at a wavelength that is different from the fourthwavelength.
 10. The system of claim 7, wherein the predeterminedbandwidth of Ethernet traffic is 80 Gbps.
 11. The system of claim 7,wherein the first device comprises an electrical interface, theelectrical interface receiving the predetermined bandwidth of Ethernettraffic over two links, each link carrying an electrical signal at 20Gbps.
 12. The system of claim 7, further comprising an optical interfaceconfigured to receive the plurality of optical fibers, the opticalinterface including four ports, each of the four ports configured toreceive one of the plurality of optical fibers.
 13. The system of claim7, further comprising a heat sink configured to dissipate heat away fromat least one of the first device or the second device.
 14. A methodcomprising: allocating, with a modem, a received predetermined bandwidthof Ethernet traffic into first and second portions; transmitting, from afirst device to a second device via a Quad Small Form-Factor Pluggable(QSFP) optical interface, the first portion of the predeterminedbandwidth of Ethernet traffic over a first optical fiber at a firstwavelength and over a second optical fiber at a second wavelength;receiving, by the first device from the second device via the QSFPoptical interface, a first return optical signal over the first opticalfiber at a wavelength different from the first wavelength and a secondreturn optical signal over the second optical fiber at a wavelength thatis different from the second wavelength; and transmitting, from thefirst device to the second device via the QSFP optical interface, thesecond portion of the predetermined bandwidth of Ethernet traffic over athird optical fiber at a third wavelength and over a fourth opticalfiber at a fourth wavelength; wherein the first optical fiber isconfigured to bidirectionally carry two wavelengths of light, the secondoptical fiber is configured to bidirectionally carry two wavelengths oflight different than the first optical fiber.
 15. The method of claim14, further comprising: receiving, by the first device from the seconddevice via the QSFP optical interface, a third return optical signalover the third optical fiber at a wavelength that is different from thethird wavelength and a fourth return optical signal over the fourthoptical fiber at a wavelength that is different from the fourthwavelength.
 16. The method of claim 14, wherein the predeterminedbandwidth of Ethernet traffic is 80 Gbps, and wherein the first portionand the second portion of the predetermined bandwidth of Ethernettraffic are each 40 Gbps.
 17. The method of claim 14, wherein the firstportion of the predetermined bandwidth of Ethernet traffic transmittedover the first optical fiber and the second optical fiber are each 20Gbps.
 18. The method of claim 14, wherein the second portion of theEthernet traffic transmitted over the third optical fiber and the fourthoptical fiber are each 20 Gbps.
 19. The method of claim 14, furthercomprising receiving, by the first device, the predetermined bandwidthof Ethernet traffic over two links, each link carrying an electricalsignal at 20 Gbps.
 20. The method of claim 14, further comprising:dissipating heat away from at least one of the first device or thesecond device.